US20080093112A1 - Composite Via Structures and Filters in Multilayer Printed Circuit Boards - Google Patents
Composite Via Structures and Filters in Multilayer Printed Circuit Boards Download PDFInfo
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- US20080093112A1 US20080093112A1 US11/658,004 US65800406A US2008093112A1 US 20080093112 A1 US20080093112 A1 US 20080093112A1 US 65800406 A US65800406 A US 65800406A US 2008093112 A1 US2008093112 A1 US 2008093112A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
- H01P1/201—Filters for transverse electromagnetic waves
- H01P1/203—Strip line filters
- H01P1/2039—Galvanic coupling between Input/Output
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/0213—Electrical arrangements not otherwise provided for
- H05K1/0216—Reduction of cross-talk, noise or electromagnetic interference
- H05K1/0218—Reduction of cross-talk, noise or electromagnetic interference by printed shielding conductors, ground planes or power plane
- H05K1/0219—Printed shielding conductors for shielding around or between signal conductors, e.g. coplanar or coaxial printed shielding conductors
- H05K1/0222—Printed shielding conductors for shielding around or between signal conductors, e.g. coplanar or coaxial printed shielding conductors for shielding around a single via or around a group of vias, e.g. coaxial vias or vias surrounded by a grounded via fence
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/0213—Electrical arrangements not otherwise provided for
- H05K1/0237—High frequency adaptations
- H05K1/025—Impedance arrangements, e.g. impedance matching, reduction of parasitic impedance
- H05K1/0251—Impedance arrangements, e.g. impedance matching, reduction of parasitic impedance related to vias or transitions between vias and transmission lines
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/11—Printed elements for providing electric connections to or between printed circuits
- H05K1/115—Via connections; Lands around holes or via connections
- H05K1/116—Lands, clearance holes or other lay-out details concerning the surrounding of a via
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/16—Printed circuits incorporating printed electric components, e.g. printed resistor, capacitor, inductor
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/0213—Electrical arrangements not otherwise provided for
- H05K1/0237—High frequency adaptations
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/09—Shape and layout
- H05K2201/09209—Shape and layout details of conductors
- H05K2201/095—Conductive through-holes or vias
- H05K2201/09618—Via fence, i.e. one-dimensional array of vias
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/09—Shape and layout
- H05K2201/09209—Shape and layout details of conductors
- H05K2201/095—Conductive through-holes or vias
- H05K2201/09627—Special connections between adjacent vias, not for grounding vias
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/09—Shape and layout
- H05K2201/09209—Shape and layout details of conductors
- H05K2201/09654—Shape and layout details of conductors covering at least two types of conductors provided for in H05K2201/09218 - H05K2201/095
- H05K2201/09718—Clearance holes
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/09—Shape and layout
- H05K2201/09209—Shape and layout details of conductors
- H05K2201/09654—Shape and layout details of conductors covering at least two types of conductors provided for in H05K2201/09218 - H05K2201/095
- H05K2201/09781—Dummy conductors, i.e. not used for normal transport of current; Dummy electrodes of components
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/09—Shape and layout
- H05K2201/09209—Shape and layout details of conductors
- H05K2201/09654—Shape and layout details of conductors covering at least two types of conductors provided for in H05K2201/09218 - H05K2201/095
- H05K2201/09809—Coaxial layout
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/10—Details of components or other objects attached to or integrated in a printed circuit board
- H05K2201/10007—Types of components
- H05K2201/1006—Non-printed filter
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
- H05K3/42—Plated through-holes or plated via connections
- H05K3/429—Plated through-holes specially for multilayer circuits, e.g. having connections to inner circuit layers
Definitions
- This invention relates generally to via structures and filters in multilayer printed circuit boards (PCBs). More specifically, the invention relates to composite via structures providing new compact filters including bandpass and bandstop ones in the multilayer PCB.
- PCBs printed circuit boards
- a via structure in a multilayer printed circuit board serves as a vertical transition between planar interconnected circuits based on planar transmission lines such as microstrip lines, striplines, coplanar lines and so on formed at different conductor layers of the PCB and are developed under the conditions providing low return and radiation (leakage) losses whole interconnect circuits used in electronic devices.
- planar transmission lines such as microstrip lines, striplines, coplanar lines and so on formed at different conductor layers of the PCB and are developed under the conditions providing low return and radiation (leakage) losses whole interconnect circuits used in electronic devices.
- planar transmission line stubs such as open- or short-circuited stubs are usually used.
- Variety of forms and dimensions of planar transmission line stubs be applied as building blocks gives a possibility to develop lowpass, highpass, bandstop and bandpass filters at different frequency bands.
- a planar structure of transmission line resonant stubs can lead to comparably large dimensions of filters as for an example at the frequency band up to 20 GHz.
- radiation (leakage) losses can be considerable in such discontinuities as planar transmission line stubs.
- First functional part extends in the vertical direction from the first pad disposed at the one side of the PCB to the special pad embedded in the PCB for the connection to a planar transmission line and serves to implement a high-performance vertical transition between the first and special pads.
- this functional part includes a signal via conductor connected to the first and special pads, a clearance hole, and ground vias surrounding the signal via conductor.
- Second functional part of the composite via structure forms a resonant length (stub) extended in the vertical direction from the special pad to the second pad disposed at the opposite side of the PCB.
- this functional part includes the same signal via conductor connected to the second pad, ground vias surrounding the signal via conductor, but besides that conductive plates are formed at the conductor layers of the PCB. Each conductive plate is connected to the signal via conductor and is isolated from grounding conductors by an isolating slot.
- Control of the resonance frequency of such stubs can be carried out by an appropriate choice of dimensions and forms of the conductive plates in the second part of the composite via structure.
- Open- and short-circuited resonant stubs, as parts of composite via structure, connected to the transmission line by means of the special pad act as compact filters.
- the first pad can be registered with the special pad in the composite via structure.
- the composite via structure including open- or short-circuited resonant stub can be connected to a microstrip line to form a compact filter.
- Three-dimensional arrangement of conductors in a filter developed by the use of composite via structures provides its compactness and the application of the ground vias provides its shielding and a high electrical performance.
- FIGS. 1A, 1B , 1 C and 1 D show perspective, cross-sectional, top and bottom views, respectively, of a composite via structure intended to form shielded open-circuited resonant stub in a multilayer PCB;
- FIGS. 2A, 2B and 2 C show cross-sectional, top and bottom views, respectively, of a composite via structure intended to form shielded open-circuited resonant stub in a multilayer PCB and including two different assemblies of ground vias;
- FIGS. 3A, 3B , 3 C and 3 D show perspective, cross-sectional, top and bottom views, respectively, of a composite via structure intended to form shielded short-circuited resonant stub in a multilayer PCB;
- FIGS. 4A, 4B and 4 C show cross-sectional, top and bottom views, respectively, of a composite via structure intended to form shielded short-circuited resonant stub in a multilayer PCB and including two different assemblies of ground vias;
- FIGS. 5A and 5B show perspective and cross-sectional views, respectively, of a filter due to forming an open-circuited resonant stub obtained by the connection of a composite via structure to a stripline in a multilayer PCB;
- FIGS. 6A and 6B show perspective and cross-sectional views, respectively, of a filter due to forming a short-circuited resonant stub obtained by the connection of a composite via structure to a stripline in a multilayer PCB;
- FIGS. 7A, 7B , 7 C and 7 D show perspective, cross-sectional, top and bottom views, respectively, of a filter formed by two open-circuited resonant stubs and provided by the connection of two composite via structures by means of a microstrip line in a multilayer PCB;
- FIGS. 8A, 8B , 8 C and 8 D show perspective, cross-sectional, top and bottom views, respectively, of a filter formed by two short-circuited resonant stubs and provided by the connection of two composite via structures by means of a microstrip line in a multilayer PCB;
- FIGS. 9A and 9B show perspective, cross-sectional, top and bottom views, respectively, of a filter formed by two open-circuited resonant stubs and provided by the connection of two composite via structures by means of a stripline in a multilayer PCB;
- FIGS. 10A and 10B show perspective, cross-sectional, top and bottom views, respectively, of a filter formed by two short-circuited resonant stubs and provided by the connection of two composite via structures by means of a stripline in a multilayer PCB;
- FIG. 11 shows a top view of a filter formed by two composite via structures in which each signal via conductor is surrounded by an assembly of ground vias with a round arrangement in a multilayer PCB;
- FIG. 12 shows a top view of a filter formed by four composite via structures in a multilayer PCB
- FIG. 13 shows simulation results of magnitudes of S-parameters for a filter formed by a composite via structure providing an open-circuited stub and a stripline in an eight-conductor-layer PCB;
- FIG. 14 shows simulation results of magnitudes of S-parameters for a filter formed by a composite via structure providing an short-circuited stub and a stripline in an eight-conductor-layer PCB;
- FIG. 15 shows simulation results of magnitudes of S-parameters for a filter formed by two composite via structures connected by means of a stripline providing two open-circuited stubs in an eight-conductor-layer PCB;
- FIG. 16 shows simulation results of magnitudes of S-parameters for a filter formed by two composite via structures connected by means of a stripline providing two short-circuited stubs in an eight-conductor-layer PCB;
- FIGS. 1A, 1B , 1 C and 1 D a composite via structure in a 7-conductor-layer PCB, which serves only as an example of multilayer PCB design, is shown in FIGS. 1A, 1B , 1 C and 1 D.
- the arrangement of conductor layers of the PCB separated by an isolating material 116 is as follows: Ground planes are 1L1, 1L3, 1L5 and 1L7 layers; Power supplying plane is 1L4 layer; and signal planes are 1L2 and 1L6 layers.
- the composite via structure unites two functional parts. First functional part provides a high-performance vertical transition from the first pad 104 to the special pad 105 disposed at the signal layer 1 L 2 .
- Second functional part of the composite via structure is intended to provide a resonant open-circuited stub extended in the vertical direction from the special pad 105 to the second pad 112 .
- this functional part includes the same signal via conductor 101 , the same assembly of ground vias 102 , and conductive plates 106 , 108 , 109 and 111 are connected to the signal via conductor 101 .
- ground vias 102 provides not only shielding of the open-circuited resonant stub but also its high quality factor (Q-factor).
- FIGS. 2A, 2B and 2 C show a composite via structure in an 8-conductor-layer PCB compounding two functional parts.
- First functional part is extended in the vertical direction from the first pad 204 to the special pad 205 serving to connect a planar transmission line formed at the same conductor layer 2 L 3 to the composite via structure.
- Second functional part is extended in the vertical direction from the special pad 205 to the second pad 212 .
- a distinguishing feature of this composite via structure is the use of two different assemblies of ground vias surrounding the signal via conductor 201 .
- ground vias 202 A is applied to form a high-performance vertical transition in the first functional part of the composite via structure and is extended in the vertical direction from the conductor layer 2 L 1 to the ground layer 2 L 4 participating in forming a planar transmission line at the conductor layer 2 L 3 .
- Another assembly of ground vias 202 B surrounding the signal via conductor 201 is used to provide the shielding and a high Q-factor resonant open-circuited stub in which the second pad 212 is separated by an isolating slot 213 from grounding conductor at the conductor layer 2 L 8 .
- FIGS. 3A, 3B , 3 C and 3 D another composite via structure in a 7-conductor-layer PCB is shown.
- This composite via structure includes two functional parts.
- the first functional part provides a high-performance vertical transition from the first pad 304 to the special pad 305 disposed at the signal layer 3 L 2 .
- This vertical transition includes a signal via conductor 301 , an assembly of ground vias 302 surrounding the signal via conductor 301 and a clearance hole 303 .
- the second functional part is intended to provide a resonant short-circuited stub extended in the vertical directions from the special pad 305 to the second pad 312 disposed at the conductor layer 3 L 7 of the PCB.
- This functional part includes the same signal via conductor 301 , the same assembly of ground vias 302 , and conductive plates 306 , 308 , 309 and 311 connected to the signal via conductor 301 .
- These conductive plates are separated from other conductors of the PCB by isolating slots and serve to control the resonance frequency of the short-circuited stub.
- isolating slots 307 and 310 are provided at the ground layers of the PCB. Short-circuited resonant stub is formed due to the connection of the second pad 312 to the ground plane disposed at the conductor layer 3 L 7 .
- FIGS. 4A, 4B and 4 C show a composite via structure in an 8-conductor-layer PCB compounding two functional parts.
- First functional part is extended in the vertical direction from the first pad 404 to the special pad 405 serving for connection of a planar transmission line formed at the same conductor layer 4 L 3 to the composite via structure.
- Second functional part is extended in the vertical direction from the special pad 405 to the ground plane disposed at the conductor layer 4 L 8 .
- this composite via structure two different assemblies of ground vias surrounding the signal via conductor 401 are used.
- ground vias 402 A is applied to form a high-performance vertical transition in the first functional part of the composite via structure and is extended in the vertical direction from the conductor layer 4 L 1 to the ground layer 4 L 4 participating in forming a planar transmission line at the conductor layer 4 L 3 .
- Another assembly of ground vias 402 B surrounding the same signal via conductor 401 is used to provide the shielding and high Q-factor resonant short-circuited stub in which the second pad is connected to the ground plane at the conductor layer 4 L 8 .
- FIGS. 5A and 5B show perspective and cross-sectional views, respectively, of a filter in an 8-conductor-layer PCB.
- This filter is formed by a composite via structure providing an open-circuited resonant stub and a stripline 515 formed at the 5L3 conductor layer of the PCB and connected to the composite via structure by means of the special pad 505 .
- Position of the resonance frequency of the filter can be controlled by dimensions of the conductive plates 506 , 508 , 509 and 511 and second pad 512 at the eight conductor layer of the PCB connected to a signal via conductor 501 and separated from ground conductor by an isolating slot 513 .
- Shielding and high Q-factor of the filter is provided by the use of an assembly of ground vias 502 .
- Input/output ports of the filter are at the first pad 504 of the composite via structure and the stripline 515 as shown in FIGS. 5A and 5B .
- resonance frequencies of the filter like that shown in FIGS. 5A and 5B
- three-dimensional full-wave electromagnetic field simulations are necessary due to a complicated three-dimensional structure of the filter.
- the finite-difference time-domain (FDTD) algorithm can be used to define complex scattering (S-parameter) matrix which is defined as the quotient between the output signal spectrum and the input signal spectrum.
- S-parameter complex scattering
- a three-dimensional full-wave simulator can be applied to calculate the electrical performance of the filter and its resonance frequencies.
- a desired resonance frequency of the filter by a gradual change of the dimensions of conductive plates connected to the signal via conductor and the second pad in the second functional part of the filter.
- FIGS. 6A and 6B show perspective and cross-sectional views, respectively, of a filter in an 8-conductor-layer PCB.
- This filter is formed by a composite via structure providing a short-circuited resonant stub and a stripline 615 formed at the conductor layer 6 L 3 of the PCB connected to the composite via structure by means of the special pad 605 .
- Position of the resonance frequency of the filter can be controlled by dimensions of the conductive plates 606 , 608 , 609 and 611 connected to a signal via conductor 601 .
- Shielding and high Q-factor of the filter is provided by the use of an assembly of ground vias 602 .
- the second pad of the composite via structure is connected to ground plate at the conductor layer 6 L 8 of the PCB. Ports of the filter are at the first pad 604 of the composite via structure and the stripline 615 as shown in FIGS. 6A and 6B .
- FIGS. 7A, 7B , 7 C and 7 D perspective, cross-sectional, top and bottom views of a filter designed by the use two composite via structures in a 7-conductor-layer PCB are shown. These composite via structures are connected by means of a microstrip line 715 . Ports of the filters are first pads 704 which are registered with specials pads of the composite via structures. Open-circuited resonant stubs of the filters are obtained by the separation of the second pads 712 of the composite via structures by isolating slots 713 . Control of bandpass and bandstop characteristics of the filter can be carried out by an appropriate choice of the dimensions of the conductive plates connected to the signal via conductors 701 and dimensions of the second pads 712 . Also optimization of the parameters of the filter can be provided by the determination of an appropriate length of the microstrip line 715 . Shielding properties and high Q-factor of the filters are provided by assemblies of ground vias 702 surrounding the signal via conductors 701 .
- FIGS. 8A, 8B , 8 C and 8 D Another type of filters provided by two composite via structures connected by means of a microstrip line 815 in a 7-conductor-layer PCB is shown in FIGS. 8A, 8B , 8 C and 8 D.
- Ports of the filters are first pads 804 which are coincided with specials pads of the composite via structures.
- Short-circuited resonant stubs of the filters are obtained by the connection of the second pads of the composite via structures to ground plate disposed at the 8L7 layer.
- Control of bandpass and bandstop characteristics of the filter is carried out by an appropriate choice of the dimensions of the conductive plates connected to the signal via conductor 801 .
- optimization of the parameters of the filter can be provided by the determination of an appropriate length of the microstrip line 815 .
- Shielding properties and high Q-factor of the filters are provided by assemblies of ground vias 802 surrounding the signal via conductors 801 .
- FIGS. 9A and 9B perspective and cross-sectional views of a filter designed by the use two composite via structures in an 8-conductor-layer PCB are shown.
- Used composite via structures include two functional parts of which first functional part provide low return and leakage losses in the vertical transition from the first pads 904 to a stripline 915 connected to the composite via structures by means of special pads 905 .
- the stripline 915 and special pads 905 are disposed at the conductor layer 9 L 3 . Ports of the filter are provided at the first pads 904 of the composite via structures.
- Second functional parts of the composite via structures provide resonant open-circuited stubs of the filter extended in the vertical direction from the special pads 905 to second pads 912 of the composite via structures which are isolated by slots 913 at the conductor layer 9 L 8 .
- the second functional parts include conductive plates connected to the signal via conductors 901 and isolated from other conductors of the PCB. Control of bandpass and bandstop characteristics of the filter can be carried out by an appropriate choice of the dimensions of these conductive plates and dimensions of the second pads 912 . Also an optimization of the parameters of the filter can be provided by the determination of an appropriate length of the stripline 915 . Shielding properties and high Q-factor of the filter are provided by assemblies of ground vias 902 surrounding the signal via conductors 901 .
- FIGS. 10A and 10B show perspective and cross-sectional views of a filter designed by the use two composite via structures in an 8-conductor-layer PCB.
- the composite via structures include two functional parts of which first functional part provide low return and leakage losses in the vertical transition from the first pads 1004 to a stripline 1015 which connects two composite via structures by means of special pads 1005 .
- the stripline 1005 and special pads 1005 are disposed at the 10L3 layer. Ports of the filter are provided at the first pads 1004 of the composite via structures.
- Second functional parts of the composite via structures provide resonant short-circuited stubs of the filter extended in the vertical direction from the special pads 1005 to the second pads 1012 of the composite via structures which are connected to the ground plane at the 10L8 conductor layer.
- the second functional parts include conductive plates connected to the signal via conductors 1001 and isolated from other conductors of the PCB. Control of bandpass and bandstop characteristics of the filter can be carried out by an appropriate choice of the dimensions of these conductive plates. Also optimization of the electrical parameters of the filter can be provided by the determination of an appropriate length of the stripline 1015 . Shielding properties and high Q-factor of the filter are provided by assemblies of ground vias 1002 surrounding the signal via conductors 1001 .
- Arrangements of ground vias surrounding the signal via conductor in the composite via structure can be various. In above-mentioned cases, square arrangements of the ground vias in composite via structures were shown. It is well understood that this type of ground via arrangements is only an example used to describe a configuration of a filter formed by composite via structures. Using this example a way to determine the characteristic impedance of the first functional part of the composite via structure is shown as follows.
- the first functional part of the composite via structure with the square arrangement of ground vias can be considered in the form of the square coaxial transmission line in which the signal via conductor represents the inner conductive boundary and the assembly of ground vias surrounding the signal via conductor is replaced by the continuous conductive boundary and is considered as the outer conductive boundary of this square coaxial transmission line.
- This simplification gives a possibility to define the characteristic impedance of the first functional part as: Z sq ⁇ 60 ⁇ 1 ⁇ ⁇ ln ⁇ ( 1.0787 ⁇ R sq r rod ) ( 1 )
- Z sq is the characteristic impedance of the first functional part of the composite via structure
- ⁇ is the relative permittivity of the PCB isolating material for which the relative permeability is equal to 1.
- the Eq. 1 can be used to define the characteristic impedance of the first functional part of the composite via structure with a square arrangement of ground vias that is necessary to provide characteristic impedance matching of the first functional part and other interconnected structures.
- FIG. 11 an example of another arrangement of ground vias in the composite via structure is shown.
- ground vias 1102 are equally spaced around a signal via conductor 1101 .
- the simplified formula used for the determination of the characteristic impedance of a round coaxial transmission line can be also applied.
- a filter can be provided by a different number of composite via structures in a multilayer PCB which can form short-circuited stubs, or open-circuited stubs, or a composition of short- and open-circuited stubs in the PCB.
- a top of view of a filter consisting of four composite via structures is shown in FIG. 12 .
- composite via structures consisting of signal via conductors 1201 and assemblies of ground vias 1202 are connected by means of microstrip lines 1215 . Two ports of the filter are also shown in the figure.
- results include magnitudes of the S-parameters against frequency calculated by the finite-difference time-domain (FDTD) algorithm, which is one of the most accurate numerical methods to characterize three-dimensional structures.
- FDTD finite-difference time-domain
- FIG. 13 magnitudes of S-parameters of a filter consisting of a composite via structure forming an open-circuited stub and a stripline in an 8-conductor layer PCB are shown.
- Arrangement of ground vias surrounding the signal via conductor has a square form and the geometry of the filter is similar to that shown in FIGS. 5 a and 5 b .
- But only the all additional conductive plates connected to the signal via conductor have round shapes with the centers on the axis of the signal via conductor.
- the radius of these additional plates and also the second pad of the composite via structure is 0.7 mm.
- the conductive plates are separated from ground plates by isolating slots of the 0.125-mm width.
- the outer diameter of the signal via conductor and ground vias is 0.3 mm; the distance between the centers of neighboring ground vias in the composite via structure is 1.1 mm; the width of the stripline is 0.12 mm; the diameter of the first and special pads is 0.6 mm; the clearance hole diameter in the first functional part of the composite via structure is 1.65 mm; the thickness of the PCB including all conductor layers is 2.5 mm; the distance between the first pad and special pads in the PCB is 0.435 mm.
- a material isolating the conductive layers of the PCB has the relative permittivity of 4.2 and is considered as lossless one. From presented results the high Q-factor bandstop effect is clearly traced at the central frequency about 7.3 GHz.
- this example demonstrates a possibility to form a high-performance bandstop filter using a composite via structure of such type.
- FIG. 14 Magnitudes of S-parameters of a filter consisting of a composite via structure forming a short-circuited stub and a stripline in an 8-conductor layer PCB are shown in FIG. 14 .
- the geometry and dimensions of the filter are the same as in FIG. 13 , but the second pad of the composite via structure is connected to the ground plane disposed at the eight conductor layer (see FIGS. 6A and 6B ).
- Presented data demonstrate the bandpass effect with the central resonance frequency about 8.2 GHz.
- this example of the bandpass filters shows applicability of invented composite via structures to design bandpass filtering components in multilayer PCBs.
- FIG. 15 magnitudes of S-parameters for a filter consisting of two same composite via structures in an 8-conductor layer PCB are shown.
- Two composite via structures form two open-circuited resonant stubs and are connected by means of a stripline.
- Dimensions of the composite via structure and the stripline are the same as for FIG. 13 and the distance between the centers of signal via conductors of the composite via structures is 2.2 mm.
- Two ports of the filter are at the first pads of the composite via structures as shown in FIGS. 9A and 9B . From FIG. 15 one can define clear bandstop and bandpass properties of the filter.
- FIG. 16 shows magnitudes of S-parameters for a filter consisting also of two same composite via structures in an 8-conductor layer PCB. But in this case two composite via structures have two short-circuited resonant stubs and are connected by means of a stripline. Note that second pads of considered composite via structures are connected to the ground plate at the eight conductor layer of the PCB (see FIGS. 10A and 10B ). Dimensions of the composite via structure and the stripline are the same as for FIG. 13 and the distance between the centers of the signal via conductors of the composite via structures is 2.2 mm. Two ports of the filter are at the first pads of the composite via structures as shown in FIGS. 10A and 10B . From FIG. 16 one can define clear bandpass properties of the filter at the frequency band from about 7 GHz to 12 GHz.
- filtering structures can be also implemented in System-on-Package, System-in-Package, and System-on-Package-on-Board.
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Abstract
Description
- This invention relates generally to via structures and filters in multilayer printed circuit boards (PCBs). More specifically, the invention relates to composite via structures providing new compact filters including bandpass and bandstop ones in the multilayer PCB.
- Usually a via structure in a multilayer printed circuit board (PCB) serves as a vertical transition between planar interconnected circuits based on planar transmission lines such as microstrip lines, striplines, coplanar lines and so on formed at different conductor layers of the PCB and are developed under the conditions providing low return and radiation (leakage) losses whole interconnect circuits used in electronic devices. These conditions stimulate the development different via structures such as blind vias, buried vias, shielded vias and so on.
- To develop components and devices based on PCB technologies, in particular filters, resonant lengths of the planar transmission lines such as open- or short-circuited stubs are usually used. Variety of forms and dimensions of planar transmission line stubs be applied as building blocks gives a possibility to develop lowpass, highpass, bandstop and bandpass filters at different frequency bands. However, a planar structure of transmission line resonant stubs can lead to comparably large dimensions of filters as for an example at the frequency band up to 20 GHz. Also radiation (leakage) losses can be considerable in such discontinuities as planar transmission line stubs.
- It is an object of the present invention to provide a composite via structure for a multilayer PCB uniting two functional parts. First functional part extends in the vertical direction from the first pad disposed at the one side of the PCB to the special pad embedded in the PCB for the connection to a planar transmission line and serves to implement a high-performance vertical transition between the first and special pads. In addition to the first and special pads, this functional part includes a signal via conductor connected to the first and special pads, a clearance hole, and ground vias surrounding the signal via conductor. Second functional part of the composite via structure forms a resonant length (stub) extended in the vertical direction from the special pad to the second pad disposed at the opposite side of the PCB. In additional to the second pad, this functional part includes the same signal via conductor connected to the second pad, ground vias surrounding the signal via conductor, but besides that conductive plates are formed at the conductor layers of the PCB. Each conductive plate is connected to the signal via conductor and is isolated from grounding conductors by an isolating slot.
- It is another object to provide a compact filter in a multilayer PCB by means of the connection of the special pad of a composite via structure to a planar transmission line where the second functional part of the composite via structure forms open- or short-circuited resonant stub as a result of the isolation of the second pad of the composite via structure from ground conductors or the connection of the second pad to the ground conductors, respectively. Control of the resonance frequency of such stubs can be carried out by an appropriate choice of dimensions and forms of the conductive plates in the second part of the composite via structure. Open- and short-circuited resonant stubs, as parts of composite via structure, connected to the transmission line by means of the special pad act as compact filters. The first pad can be registered with the special pad in the composite via structure. In this case the composite via structure including open- or short-circuited resonant stub can be connected to a microstrip line to form a compact filter.
- It is another object to provide different types of filters formed in a multilayer PCB as for example bandstop and bandpass ones by the use of a number of composite via structures with open- and short-circuited resonant stubs connected by means of the planar transmission line through the special pads of the composite via structures.
- Three-dimensional arrangement of conductors in a filter developed by the use of composite via structures provides its compactness and the application of the ground vias provides its shielding and a high electrical performance.
-
FIGS. 1A, 1B , 1C and 1D show perspective, cross-sectional, top and bottom views, respectively, of a composite via structure intended to form shielded open-circuited resonant stub in a multilayer PCB; -
FIGS. 2A, 2B and 2C show cross-sectional, top and bottom views, respectively, of a composite via structure intended to form shielded open-circuited resonant stub in a multilayer PCB and including two different assemblies of ground vias; -
FIGS. 3A, 3B , 3C and 3D show perspective, cross-sectional, top and bottom views, respectively, of a composite via structure intended to form shielded short-circuited resonant stub in a multilayer PCB; -
FIGS. 4A, 4B and 4C show cross-sectional, top and bottom views, respectively, of a composite via structure intended to form shielded short-circuited resonant stub in a multilayer PCB and including two different assemblies of ground vias; -
FIGS. 5A and 5B show perspective and cross-sectional views, respectively, of a filter due to forming an open-circuited resonant stub obtained by the connection of a composite via structure to a stripline in a multilayer PCB; -
FIGS. 6A and 6B show perspective and cross-sectional views, respectively, of a filter due to forming a short-circuited resonant stub obtained by the connection of a composite via structure to a stripline in a multilayer PCB; -
FIGS. 7A, 7B , 7C and 7D show perspective, cross-sectional, top and bottom views, respectively, of a filter formed by two open-circuited resonant stubs and provided by the connection of two composite via structures by means of a microstrip line in a multilayer PCB; -
FIGS. 8A, 8B , 8C and 8D show perspective, cross-sectional, top and bottom views, respectively, of a filter formed by two short-circuited resonant stubs and provided by the connection of two composite via structures by means of a microstrip line in a multilayer PCB; -
FIGS. 9A and 9B show perspective, cross-sectional, top and bottom views, respectively, of a filter formed by two open-circuited resonant stubs and provided by the connection of two composite via structures by means of a stripline in a multilayer PCB; -
FIGS. 10A and 10B show perspective, cross-sectional, top and bottom views, respectively, of a filter formed by two short-circuited resonant stubs and provided by the connection of two composite via structures by means of a stripline in a multilayer PCB; -
FIG. 11 shows a top view of a filter formed by two composite via structures in which each signal via conductor is surrounded by an assembly of ground vias with a round arrangement in a multilayer PCB; -
FIG. 12 shows a top view of a filter formed by four composite via structures in a multilayer PCB; -
FIG. 13 shows simulation results of magnitudes of S-parameters for a filter formed by a composite via structure providing an open-circuited stub and a stripline in an eight-conductor-layer PCB; -
FIG. 14 shows simulation results of magnitudes of S-parameters for a filter formed by a composite via structure providing an short-circuited stub and a stripline in an eight-conductor-layer PCB; -
FIG. 15 shows simulation results of magnitudes of S-parameters for a filter formed by two composite via structures connected by means of a stripline providing two open-circuited stubs in an eight-conductor-layer PCB; -
FIG. 16 shows simulation results of magnitudes of S-parameters for a filter formed by two composite via structures connected by means of a stripline providing two short-circuited stubs in an eight-conductor-layer PCB; - The following description of the preferred embodiments directed to only several examples of composite via structures and filters provided by the use of some composite via structures but it is well understood that this description should not be viewed as narrowing the claims which follows.
- Referring to the drawings, a composite via structure in a 7-conductor-layer PCB, which serves only as an example of multilayer PCB design, is shown in
FIGS. 1A, 1B , 1C and 1D. In these figures, the arrangement of conductor layers of the PCB separated by anisolating material 116 is as follows: Ground planes are 1L1, 1L3, 1L5 and 1L7 layers; Power supplying plane is 1L4 layer; and signal planes are 1L2 and 1L6 layers. The composite via structure unites two functional parts. First functional part provides a high-performance vertical transition from thefirst pad 104 to thespecial pad 105 disposed at the signal layer 1L2. Low return and leakage losses of this vertical transition including a signal viaconductor 101, an assembly ofground vias 102 surrounding the signal viaconductor 101 and aclearance hole 103 are realized by means of controlling the characteristic impedance of the vertical transition using an appropriate interval between the signal viaconductor 101 and theground vias 102. Second functional part of the composite via structure is intended to provide a resonant open-circuited stub extended in the vertical direction from thespecial pad 105 to thesecond pad 112. In additional to thesecond pad 112, this functional part includes the same signal viaconductor 101, the same assembly ofground vias 102, andconductive plates conductor 101. These conductive plates are isolated from other conductors of the PCB by isolating slots and serve to control the resonance frequency of the open-circuited stub. As for an example at the ground layers of thePCB isolating slots second pad 112 is separated from the grounding conductors at the conductor layer 1L7 by anisolating slot 113. Note that the assembly ofground vias 102 provides not only shielding of the open-circuited resonant stub but also its high quality factor (Q-factor). -
FIGS. 2A, 2B and 2C show a composite via structure in an 8-conductor-layer PCB compounding two functional parts. First functional part is extended in the vertical direction from thefirst pad 204 to thespecial pad 205 serving to connect a planar transmission line formed at the same conductor layer 2L3 to the composite via structure. Second functional part is extended in the vertical direction from thespecial pad 205 to thesecond pad 212. A distinguishing feature of this composite via structure is the use of two different assemblies of ground vias surrounding the signal viaconductor 201. One assembly ofground vias 202A is applied to form a high-performance vertical transition in the first functional part of the composite via structure and is extended in the vertical direction from the conductor layer 2L1 to the ground layer 2L4 participating in forming a planar transmission line at the conductor layer 2L3. Another assembly ofground vias 202B surrounding the signal viaconductor 201 is used to provide the shielding and a high Q-factor resonant open-circuited stub in which thesecond pad 212 is separated by an isolatingslot 213 from grounding conductor at the conductor layer 2L8. - In
FIGS. 3A, 3B , 3C and 3D, another composite via structure in a 7-conductor-layer PCB is shown. This composite via structure includes two functional parts. The first functional part provides a high-performance vertical transition from thefirst pad 304 to thespecial pad 305 disposed at the signal layer 3L2. This vertical transition includes a signal viaconductor 301, an assembly of ground vias 302 surrounding the signal viaconductor 301 and aclearance hole 303. The second functional part is intended to provide a resonant short-circuited stub extended in the vertical directions from thespecial pad 305 to thesecond pad 312 disposed at the conductor layer 3L7 of the PCB. This functional part includes the same signal viaconductor 301, the same assembly ofground vias 302, andconductive plates conductor 301. These conductive plates are separated from other conductors of the PCB by isolating slots and serve to control the resonance frequency of the short-circuited stub. At the ground layers of the PCB, as shown in theFIG. 3A , isolatingslots second pad 312 to the ground plane disposed at the conductor layer 3L7. -
FIGS. 4A, 4B and 4C show a composite via structure in an 8-conductor-layer PCB compounding two functional parts. First functional part is extended in the vertical direction from thefirst pad 404 to thespecial pad 405 serving for connection of a planar transmission line formed at the same conductor layer 4L3 to the composite via structure. Second functional part is extended in the vertical direction from thespecial pad 405 to the ground plane disposed at the conductor layer 4L8. In this composite via structure two different assemblies of ground vias surrounding the signal viaconductor 401 are used. One assembly ofground vias 402A is applied to form a high-performance vertical transition in the first functional part of the composite via structure and is extended in the vertical direction from the conductor layer 4L1 to the ground layer 4L4 participating in forming a planar transmission line at the conductor layer 4L3. Another assembly ofground vias 402B surrounding the same signal viaconductor 401 is used to provide the shielding and high Q-factor resonant short-circuited stub in which the second pad is connected to the ground plane at the conductor layer 4L8. -
FIGS. 5A and 5B show perspective and cross-sectional views, respectively, of a filter in an 8-conductor-layer PCB. This filter is formed by a composite via structure providing an open-circuited resonant stub and astripline 515 formed at the 5L3 conductor layer of the PCB and connected to the composite via structure by means of thespecial pad 505. Position of the resonance frequency of the filter can be controlled by dimensions of theconductive plates second pad 512 at the eight conductor layer of the PCB connected to a signal viaconductor 501 and separated from ground conductor by an isolatingslot 513. Shielding and high Q-factor of the filter is provided by the use of an assembly ofground vias 502. Input/output ports of the filter are at thefirst pad 504 of the composite via structure and thestripline 515 as shown inFIGS. 5A and 5B . - It should be noted to define resonance frequencies of the filter like that shown in
FIGS. 5A and 5B , three-dimensional full-wave electromagnetic field simulations are necessary due to a complicated three-dimensional structure of the filter. As for an example, the finite-difference time-domain (FDTD) algorithm can be used to define complex scattering (S-parameter) matrix which is defined as the quotient between the output signal spectrum and the input signal spectrum. For this aim, a three-dimensional full-wave simulator can be applied to calculate the electrical performance of the filter and its resonance frequencies. Also one can define a desired resonance frequency of the filter by a gradual change of the dimensions of conductive plates connected to the signal via conductor and the second pad in the second functional part of the filter. -
FIGS. 6A and 6B show perspective and cross-sectional views, respectively, of a filter in an 8-conductor-layer PCB. This filter is formed by a composite via structure providing a short-circuited resonant stub and astripline 615 formed at the conductor layer 6L3 of the PCB connected to the composite via structure by means of thespecial pad 605. Position of the resonance frequency of the filter can be controlled by dimensions of theconductive plates conductor 601. Shielding and high Q-factor of the filter is provided by the use of an assembly ofground vias 602. The second pad of the composite via structure is connected to ground plate at the conductor layer 6L8 of the PCB. Ports of the filter are at thefirst pad 604 of the composite via structure and thestripline 615 as shown inFIGS. 6A and 6B . - In
FIGS. 7A, 7B , 7C and 7D perspective, cross-sectional, top and bottom views of a filter designed by the use two composite via structures in a 7-conductor-layer PCB are shown. These composite via structures are connected by means of amicrostrip line 715. Ports of the filters arefirst pads 704 which are registered with specials pads of the composite via structures. Open-circuited resonant stubs of the filters are obtained by the separation of thesecond pads 712 of the composite via structures by isolatingslots 713. Control of bandpass and bandstop characteristics of the filter can be carried out by an appropriate choice of the dimensions of the conductive plates connected to the signal viaconductors 701 and dimensions of thesecond pads 712. Also optimization of the parameters of the filter can be provided by the determination of an appropriate length of themicrostrip line 715. Shielding properties and high Q-factor of the filters are provided by assemblies of ground vias 702 surrounding the signal viaconductors 701. - Another type of filters provided by two composite via structures connected by means of a
microstrip line 815 in a 7-conductor-layer PCB is shown inFIGS. 8A, 8B , 8C and 8D. Ports of the filters arefirst pads 804 which are coincided with specials pads of the composite via structures. Short-circuited resonant stubs of the filters are obtained by the connection of the second pads of the composite via structures to ground plate disposed at the 8L7 layer. Control of bandpass and bandstop characteristics of the filter is carried out by an appropriate choice of the dimensions of the conductive plates connected to the signal viaconductor 801. Also optimization of the parameters of the filter can be provided by the determination of an appropriate length of themicrostrip line 815. Shielding properties and high Q-factor of the filters are provided by assemblies of ground vias 802 surrounding the signal viaconductors 801. - In
FIGS. 9A and 9B , perspective and cross-sectional views of a filter designed by the use two composite via structures in an 8-conductor-layer PCB are shown. Used composite via structures include two functional parts of which first functional part provide low return and leakage losses in the vertical transition from thefirst pads 904 to astripline 915 connected to the composite via structures by means ofspecial pads 905. Thestripline 915 andspecial pads 905 are disposed at the conductor layer 9L3. Ports of the filter are provided at thefirst pads 904 of the composite via structures. Second functional parts of the composite via structures provide resonant open-circuited stubs of the filter extended in the vertical direction from thespecial pads 905 tosecond pads 912 of the composite via structures which are isolated byslots 913 at the conductor layer 9L8. The second functional parts include conductive plates connected to the signal viaconductors 901 and isolated from other conductors of the PCB. Control of bandpass and bandstop characteristics of the filter can be carried out by an appropriate choice of the dimensions of these conductive plates and dimensions of thesecond pads 912. Also an optimization of the parameters of the filter can be provided by the determination of an appropriate length of thestripline 915. Shielding properties and high Q-factor of the filter are provided by assemblies of ground vias 902 surrounding the signal viaconductors 901. -
FIGS. 10A and 10B show perspective and cross-sectional views of a filter designed by the use two composite via structures in an 8-conductor-layer PCB. The composite via structures include two functional parts of which first functional part provide low return and leakage losses in the vertical transition from thefirst pads 1004 to astripline 1015 which connects two composite via structures by means ofspecial pads 1005. Thestripline 1005 andspecial pads 1005 are disposed at the 10L3 layer. Ports of the filter are provided at thefirst pads 1004 of the composite via structures. Second functional parts of the composite via structures provide resonant short-circuited stubs of the filter extended in the vertical direction from thespecial pads 1005 to thesecond pads 1012 of the composite via structures which are connected to the ground plane at the 10L8 conductor layer. The second functional parts include conductive plates connected to the signal viaconductors 1001 and isolated from other conductors of the PCB. Control of bandpass and bandstop characteristics of the filter can be carried out by an appropriate choice of the dimensions of these conductive plates. Also optimization of the electrical parameters of the filter can be provided by the determination of an appropriate length of thestripline 1015. Shielding properties and high Q-factor of the filter are provided by assemblies ofground vias 1002 surrounding the signal viaconductors 1001. - Arrangements of ground vias surrounding the signal via conductor in the composite via structure can be various. In above-mentioned cases, square arrangements of the ground vias in composite via structures were shown. It is well understood that this type of ground via arrangements is only an example used to describe a configuration of a filter formed by composite via structures. Using this example a way to determine the characteristic impedance of the first functional part of the composite via structure is shown as follows. The first functional part of the composite via structure with the square arrangement of ground vias can be considered in the form of the square coaxial transmission line in which the signal via conductor represents the inner conductive boundary and the assembly of ground vias surrounding the signal via conductor is replaced by the continuous conductive boundary and is considered as the outer conductive boundary of this square coaxial transmission line. This simplification gives a possibility to define the characteristic impedance of the first functional part as:
where Zsq is the characteristic impedance of the first functional part of the composite via structure, Rsq=Dsq/2 is the distance between the centers of the central signal via conductor and the nearest ground vias, rrod=drod/2 is the outer radius of the central conductor, ε is the relative permittivity of the PCB isolating material for which the relative permeability is equal to 1. - Thus, the Eq. 1 can be used to define the characteristic impedance of the first functional part of the composite via structure with a square arrangement of ground vias that is necessary to provide characteristic impedance matching of the first functional part and other interconnected structures.
- In
FIG. 11 , an example of another arrangement of ground vias in the composite via structure is shown. In this roundarrangement ground vias 1102 are equally spaced around a signal viaconductor 1101. Moreover, for this arrangement of ground vias the simplified formula used for the determination of the characteristic impedance of a round coaxial transmission line can be also applied. - It should be noted that a filter can be provided by a different number of composite via structures in a multilayer PCB which can form short-circuited stubs, or open-circuited stubs, or a composition of short- and open-circuited stubs in the PCB. As an example, a top of view of a filter consisting of four composite via structures is shown in
FIG. 12 . In considered case, composite via structures consisting of signal viaconductors 1201 and assemblies ofground vias 1202 are connected by means ofmicrostrip lines 1215. Two ports of the filter are also shown in the figure. - To show a possibility of the realization of invented composite via structures and filters based on the use of these structures in a multilayer PCB, some results of simulations are presented here. The results include magnitudes of the S-parameters against frequency calculated by the finite-difference time-domain (FDTD) algorithm, which is one of the most accurate numerical methods to characterize three-dimensional structures.
- In
FIG. 13 , magnitudes of S-parameters of a filter consisting of a composite via structure forming an open-circuited stub and a stripline in an 8-conductor layer PCB are shown. Arrangement of ground vias surrounding the signal via conductor has a square form and the geometry of the filter is similar to that shown inFIGS. 5 a and 5 b. But only the all additional conductive plates connected to the signal via conductor have round shapes with the centers on the axis of the signal via conductor. The radius of these additional plates and also the second pad of the composite via structure is 0.7 mm. The conductive plates are separated from ground plates by isolating slots of the 0.125-mm width. Other dimensions of the filter are as follows: The outer diameter of the signal via conductor and ground vias is 0.3 mm; the distance between the centers of neighboring ground vias in the composite via structure is 1.1 mm; the width of the stripline is 0.12 mm; the diameter of the first and special pads is 0.6 mm; the clearance hole diameter in the first functional part of the composite via structure is 1.65 mm; the thickness of the PCB including all conductor layers is 2.5 mm; the distance between the first pad and special pads in the PCB is 0.435 mm. In simulations a material isolating the conductive layers of the PCB has the relative permittivity of 4.2 and is considered as lossless one. From presented results the high Q-factor bandstop effect is clearly traced at the central frequency about 7.3 GHz. Thus, this example demonstrates a possibility to form a high-performance bandstop filter using a composite via structure of such type. - Magnitudes of S-parameters of a filter consisting of a composite via structure forming a short-circuited stub and a stripline in an 8-conductor layer PCB are shown in
FIG. 14 . The geometry and dimensions of the filter are the same as inFIG. 13 , but the second pad of the composite via structure is connected to the ground plane disposed at the eight conductor layer (seeFIGS. 6A and 6B ). Presented data demonstrate the bandpass effect with the central resonance frequency about 8.2 GHz. Thus, this example of the bandpass filters shows applicability of invented composite via structures to design bandpass filtering components in multilayer PCBs. - In
FIG. 15 , magnitudes of S-parameters for a filter consisting of two same composite via structures in an 8-conductor layer PCB are shown. Two composite via structures form two open-circuited resonant stubs and are connected by means of a stripline. Dimensions of the composite via structure and the stripline are the same as forFIG. 13 and the distance between the centers of signal via conductors of the composite via structures is 2.2 mm. Two ports of the filter are at the first pads of the composite via structures as shown inFIGS. 9A and 9B . FromFIG. 15 one can define clear bandstop and bandpass properties of the filter. -
FIG. 16 shows magnitudes of S-parameters for a filter consisting also of two same composite via structures in an 8-conductor layer PCB. But in this case two composite via structures have two short-circuited resonant stubs and are connected by means of a stripline. Note that second pads of considered composite via structures are connected to the ground plate at the eight conductor layer of the PCB (seeFIGS. 10A and 10B ). Dimensions of the composite via structure and the stripline are the same as forFIG. 13 and the distance between the centers of the signal via conductors of the composite via structures is 2.2 mm. Two ports of the filter are at the first pads of the composite via structures as shown inFIGS. 10A and 10B . FromFIG. 16 one can define clear bandpass properties of the filter at the frequency band from about 7 GHz to 12 GHz. - Presented examples demonstrate effectiveness and possibilities invented structures to provide different types of filters in multilayer PCBs.
- It should be noted that provided filtering structures can be also implemented in System-on-Package, System-in-Package, and System-on-Package-on-Board.
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Also Published As
Publication number | Publication date |
---|---|
CN100555738C (en) | 2009-10-28 |
WO2006009274A1 (en) | 2006-01-26 |
JP2008507858A (en) | 2008-03-13 |
US7705695B2 (en) | 2010-04-27 |
JP4367660B2 (en) | 2009-11-18 |
CN1989650A (en) | 2007-06-27 |
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